KAYO MOTOR TD125, Service Manual

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1. Check whether the cylinder block is worn or
damaged;
2. Measure the inner diameter of the cylinder block, take
three positions, namely the top, middle and bottom of
the piston stroke, and measure the two directions which
are at right angles to each other.
Maintenance limit value: φ52.418mm.
Removal of piston and piston ring
Piston and piston ring removal steps are as follows:
1. Remove the piston pin retainer using needle-nose
pliers.
2. Remove the piston pin.
3. Remove the piston;
4. Remove the piston rings.
Note: do not drop the piston pin retainer into the
crankcase when removing it
Inspection of piston and piston ring
Piston, piston ring inspection steps are as follows:
1. Measure od 7 mm above piston skirt.
Maintenance limit value: φ52.36mm;
2. Calculate the cylinder clearance.
Maintenance limit value: 0.1mm;
3. Measure the inner diameter of the piston pin hole.
Maintenance limit value: φ 13.017mm
4. Check whether the piston and piston ring grooves are
worn, and measure the side clearance between the piston
ring and the piston ring grooves.
Maintenance limit value: one ring: 0.08mm
Second ring: 0.08mm
Oil ring: 0.08 mm
5. Check the piston carbon deposition, if the carbon
deposition is too much, clean up in time.
6. Load the piston ring into the cylinder and measure the
closing clearance.
Maintenance limit value: one ring: 0.4mm
Second: 0.4 mm
Oil ring: 1.4 mm
7. Measure the outside diameter of the piston pin.
Maintenance limit value: φ 12.985mm
8. Calculate the clearance between the piston pin hole
and the piston pin.
Maintenance limit value: 0.025mm
Installation of piston ring